Quenching of the Photoisomerization of Azobenzene Self-Assembled Monolayers by the Metal Substrate

In this study, we aim at investigating the role played by the metal surface as a possible dissipative channel in the photoisomerization process of azobenzene-derivative-based self-assembled monolayers (azo-SAMs). In particular we compare the cases of gold and platinum. We study the excitonic transfer phenomena of two azo-derivatives (both in trans and in cis conformation) chemisorbed on Au{111} and Pt{111} to the metal surfaces. The metal effects are evaluated within the local and nonlocal regimes, showing that nonlocality in the metal response plays an important role and nonlocal accounting quenching rates are one order of magnitude smaller than the corresponding local results. The couplings are stronger for Au{111} than for Pt{111}, but for both cases the energy transfer between the molecule and the metal turns out not to be able to suppress photoisomerization.